Recently, devices for compressing and encoding an image by adopting a encoding scheme of handling image information digitally and performing compression by an orthogonal transform such as a discrete cosine transform and motion compensation using image information-specific redundancy for the purpose of information transmission and accumulation with high efficiency when the image information is handled digitally have become widespread. Moving Picture Experts Group (MPEG), H.264, MPEG-4 Part 10 (Advanced Video Coding) (hereinafter referred to as H.264/AVC), and the like are examples of such encoding schemes.
Therefore, for the purpose of improving encoding efficiency compared to H.264/AVC, standardization of a encoding scheme referred to as high efficiency video coding (HEVC) by Joint Collaboration Team-Video Coding (JCTVC), which is a joint standardizing organization of International Telecommunication Union Telecommunication Standardization Sector (ITU-T) and International Organization for Standardization (ISO)/International Electrotechnical Commission (IEC), is currently in progress, and Non-Patent Literature 1 has been issued as a draft of the scheme.
Meanwhile, the existing image encoding schemes such as MPEG-2 and AVC have a scalability function of dividing an image into a plurality of layers and encoding the plurality of layers.
In other words, for example, for a terminal having a low processing capability such as a mobile phone, image compression information of only a base layer is transmitted, and a moving image of low spatial and temporal resolutions or a low quality is reproduced, and for a terminal having a high processing capability such as a television or a personal computer, image compression information of an enhancement layer as well as a base layer is transmitted, and a moving image of high spatial and temporal resolutions or a high quality is reproduced. That is, image compression information according to a capability of a terminal or a network can be transmitted from a server without performing the transcoding process.
In the HEVC, it is possible to designate a hypothetical reference decoder (HRD) parameter so that an overflow or an underflow of a buffer does not occur when a decoding process for image compression information is performed. Particularly, it is possible to designate an HRD parameter for each layer when scalable video coding is performed (see Non-Patent Literature 2).